I don't think your argument about grace periods is very solid to be honest and not applicable in this case as the OP stayed 11 minutes beyond the end of the parking session anyway. The PPC will argue you need to purchase enough time to cover the time between entering and exiting. That's how ANPR enforcement works. If you can successfully argue that entrance and exit times aren't applicable, only the unknown period of actual parking you FUBAR the entire industry overnight. What's to stop a motorist entering a car park, parking, wandering into town, paying for parking an hour after parking. The only line of reasonable defence I can see is the Ringo receipt stating a session period. That is misleading, it should have merely stated the duration purchased.
If you have evidence the app malfunctioned preventing you from extending your parking I'd use that as clear defence, frustration of contract. Were there any other payment options you could have used, payment machines for example.
I disagree.
Firstly, the defendant has demonstrated that the driver acted reasonably in all instances - they entered the car park, parked up and paid - all done in quick succession and well within reasonable time based on the circumstances.
Secondly, if the parking operator wanted to base it's charges on 'entry time' then it could easily do that using the ANPR data which was gathered at entry - it's a the operator's commercial choice not to do that - that is not the fault of the defendant and the defendant cannot be made liable due to the inadequacies of the parking operators methods of operation.
Thirdly, this is a consumer contract dispute and , as such, the confirmation of contract will be the centre-point of the case and therefore undefeatable by the Claimant - the contents of the established contract will dictate the timings and not other implied interpretations.
Fourthly, how 'ANPR enforcement works' is irrelevant if the parking operator allows a contract to be formed which is not based on the precise entry time - the law does not exist to make ANPR enforcement workable - ANPR enforcement is demonstrably unreliable when entry / exit times are very tight (vs the parking time purchased) since entry and exit times don't actually demonstrate the exact period of parking.
Fifthly, de minimis principle - the alleged contravention period is ridiculously tiny - any claim would immediately represent unreasonable conduct by the Claimant.